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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_636_Библиотеки_им_академика_М_И_Перельмана.pdf
182
B. R. Davis and K. R. Kasten
• Supralevator abscesses are the least common.
• The “horseshoe abscess” describes a process
whereby bilateral disease occurs via connection through the intersphincteric, supralevator,
or ischiorectal spaces.
Evaluation
History andSymptoms
• The patient with an anorectal abscess presents
most commonly with acute pain in the perianal or perirectal region.
• The pain is usually worsened with sitting and
defecation.
• Associated symptoms of urinary dysfunction
may distinguish the abscess as supralevator.
• Other symptoms include fever, chills, swelling, erythema, spontaneous drainage, and
malaise.
• Past medical history can alert the clinician to
other possible causes of rectal pain including
ssure, hemorrhoids, levator spasm, sexually
transmitted infections, tuberculosis, HIV,
IBD, malignancy, and trauma.
• Given the possibility of surgical intervention,
determining sphincter function and any history
of fecal incontinence is important in these
patients.
Physical Examination
• External evaluation will reveal classic signs of
infection including erythema, induration, uctuance, pain, and spontaneous drainage.
• For patients with an intersphincteric or supralevator abscess, external review is unlikely to
reveal denitive signs; however, upon digital
rectal exam, uctuance or extreme discomfort
should alert the clinician to this diagnosis.
• Unfortunately, pain oftentimes precludes an
adequate rectal exam.
• When the diagnosis is in doubt, consideration
should be given to performance of an exam
under anesthesia with anoscopy and possible
exible sigmoidoscopy.
• Suspicion for supralevator abscess, or in
patients with complicated medical history,
further imaging may be warranted.
Imaging
Computed Tomography (CT)
• Indicated in any patient:
– When the diagnosis of anorectal abscess is
unclear
– With complex suppurative anorectal
conditions
– With signicant comorbidities in which
missing the diagnosis would prove harmful
– As a possible substitution for surgical
evaluation
• Can also be considered in patients with perianal Crohn’s disease to assist delineation of
rectal inammation from anorectal abscess.
• Triple contrast is often required (Fig.14.3 a–c).
Magnetic Resonance Imaging (MRI)
• MRI for evaluation of anorectal abscess is
uncommon, occurring more frequently in
chronic, complex stula-in-ano disease.
• Best for any recurrent of incompletely drained
abscess to assist identication of horseshoe/
postanal, supralevator, and other complex
abscesses.
Endoanal Ultrasound (EAUS)
• Familiar to most colorectal surgeons, endoanal ultrasound utilizes a probe with 2D or 3D
capabilities at a frequency of 5–16MHz.
• Similar in discomfort to anoscopy, this technology allows effective characterization of
abscesses and stulas with reported accuracy
of 85%.
14 Anorectal Abscess andFistula
183
a
b
c
Fig. 14.3 Computed tomography of complex anorectal abscess extending anteriorly toward the scrotum. Axial images
(a), coronal image (b), sagittal image (c)
Transperineal Sonography (TP-US)
• A lesser-known technique in the colorectal
Treatment
Role ofAntibiotics
eld, TP-US can be quite accurate in diagnosis of uid collections, internal opening, and
even existence and course of a stulous track.
• Most importantly, in experienced hands it distinguishes perianal from perirectal abscess
and sepsis.
• In a comparison of TP-US and MRI, the former was more accurate for supercial uid
collections, while the latter was more accurate
• The surgical principles for management of
abscesses hold true with prompt drainage and
debridement being the cornerstone.
• Antibiotics are indicated when:
– Associated cellulitis is present.
– Patients who fail to improve following
appropriate drainage.
– Immunosuppressed patients.
for perirectal infection.
184
B. R. Davis and K. R. Kasten
• Coverage is directed toward Escherichia coli,
Enterococcus species, and Bacteroides fragilis in immunocompetent patients and Neisseria
gonorrhoeae, Chlamydia trachomatis, cyto-
megalovirus, and herpes simplex virus in
immunocompromised patients.
• Consider wound culture only in high-risk
patient populations and individuals with recurrent or non-healing disease.
• Risk of stula formation was unrelated to antibiotic usage.
• Fistula formation is related to location of the
abscess with an eight times higher risk associated with ischiorectal location and a three
times higher risk with intersphincteric compared to the perianal location.
Incision andDrainage
• Simple, supercial perianal or ischiorectal
abscesses requiring external drainage at the
skin level are amenable to bedside drainage in
the ofce, emergency room, or hospital ward.
• A simple rule of thumb recommends “outward” drainage whenever an abscess enters, or
passes through, skeletal muscle (i.e., levator
ani, external sphincter).
• All others should be drained internally through
the rectum/anus.
• The choice of elliptical incision, or cruciate
incision combined with excision of skin aps,
prevents early closure and recurrence
(Fig.14.4).
• When possible, the incision is made as near
the anal verge as possible to limit the length of
any potential stula. Packing is not required in
this scenario, and its absence yields quicker
healing with less pain.
• Patients requiring internal drainage, those
with recurrent or bilateral disease, and those
with large abscesses at risk for inadequate
bedside drainage, should undergo operative
drainage.
• For abscesses of signicant size, consider
multiple counter incisions with interposition
of setons or penrose drains to accelerate
healing.
a
bc
d
Fig. 14.4 Drainage of abscess: (a) injection of local
anesthesia, (b) cruciate incision, (c) excision of skin, (d)
drainage cavity
• Drains are removed at 2–3weeks postoperatively when the base of the cavity has granulated and shrunk.
• Further candidates for internal drainage include:
1. Submucosal abscess
2. Intersphincteric abscess
3. Supralevator abscess from intersphincteric
stula
Drain
e
14 Anorectal Abscess andFistula
185
4. Supralevator abscess from pelvic disease
• The diagnosis of intersphincteric stula
should be entertained in patients with pain out
of proportion to exam ndings.
• Denitive management involves incision of
the internal sphincter along the length of
abscess, with or without marsupialization of
the wound edges.
• Supralevator abscesses require delineation of
the track by imaging before surgical correction is undertaken.
• Transrectal drainage is indicated in most
scenarios.
• Abdominal drainage can be considered
depending upon ease of access and directionality of the abscess cavity.
• When the source is intra-abdominal, percutaneous management may prevent creation of a
stulous track through the levator plate via
improper ischiorectal drainage and is often
more successful than transrectal drainage.
• The scenario of supralevator extension from
ischiorectal abscess due to a transsphincteric
stula requires ischiorectal drainage.
– For instances where a supralevator abscess
forms as an upward extension of an intersphincteric stula, internal drainage via incision of the internal sphincter is best (Fig.14.5).
• Bilateral abscess disease, or “horseshoe”
abscess, requires operative drainage to delineate and control the source.
• This difcult-to-treat entity most commonly
arises from a deep postanal space abscess.
• Options for management include the Hanley
or modied Hanley procedures, consisting of
open posterior drainage through the
anococcygeal ligament, posterior midline
incision of the internal sphincter and inciting
anal duct, and open drainage of bilateral
ischiorectal fossae to control lateral tracks
(Fig.14.6).
Don’t
Drain
Don’t
Fig. 14.6 Drainage of a
horseshoe abscess
Counter drainage
Fig. 14.5 Drainage of a supralevator abscess
Posterior drainage
External sphincter
Internal sphincter
Counter drainag
Dentate line
186
B. R. Davis and K. R. Kasten
• If necessary, a seton (cutting or non-cutting) is
placed in the posterior midline, with subsequent denitive management taking place at a
later time (Fig.14.7).
Catheter Drainage
• Appropriate size and external xation of catheter is necessary to ensure adequate drainage.
• A mushroom tip catheter (e.g., de Pezzer,
Malecot, Cook Medical) between 10 and 14
Fr is inserted to full cavity depth and secured
to the skin (Fig.14.8).
• Recommendations differ with regards to
duration of treatment, ranging from 3 to
21days.
Fig. 14.7 Horseshoe stula managed with drainage and
seton
Drainage withPrimary Fistulotomy
• Historically, primary fistulotomy was performed when draining the abscess for
source control, thereby increasing the rate
of healing without need for subsequent
procedure.
• The acute setting inammation may inhibit
clear determination of muscle involvement,
thereby increasing the risk of excessive muscle incision; placement of seton may be indicated preventing the unintended consequence
of incontinence.
• Reports indicate a high rate of spontaneous
healing following effective abscess drainage
alone with the incidence of recurrent abscess
reported to be 30% and subsequent stula formation between 26% and 50%.
• Localizing the offending duct is difcult, and
misidentication leads to complications; alternative methods are available.
– Manual pressure on the abscess cavity
while looking for purulent extrusion
– Identication of inammation indicating
the culprit duct
– Simple blind probing
– Injection of 2cc of 2% hydrogen peroxide
combined with 1–2 drops of methylene
blue into the abscess cavity
• Unfortunately, there is no clear answer to the
question of primary stulotomy at time of
abscess drainage.
• Supercial and low transsphincteric (less
than 30–40% external sphincter involvement) stulas with minimal sphincter
involvement provide the best opportunity for
successful stulotomy at the time of abscess
drainage.
Fig. 14.8 Pezzer catheter in an ischiorectal fossa abscess
Postoperative Management
• Local wound care involves sitz baths 2–3
times daily followed by wound coverage using
gauze.
• Packing is not necessary and should be
avoided.
14 Anorectal Abscess andFistula
187
• There is no data to support the use of topical
antibiotics.
• Endpoint for removal of catheters is cessation
of purulent drainage from the drain.
• Patients are followed until complete healing
of the wound or cavity, especially since recurrence and stula formation is associated with
delay/lack of surgical follow-up.
• Antibiotics are not warranted in the postoperative setting unless cellulitis is present or in the
immunocompromised patient.
Complications
Immediate Postoperative Period
• Complications related to abscess drainage and
stulotomy include bleeding (1–2%) and urinary retention (2–6%).
• Universal risk factors for urinary retention in
anorectal procedures include age over 50,
female sex, and intravenous uid (IVF) greater
than 1L perioperatively.
Abscess Recurrence andFistula
Formation
• Rates of abscess recurrence following drainage are estimated at 4–31%, with a median
of13%.
• Rates of recurrence are higher in those undergoing management more than 7 days after
onset of symptoms.
• Early recurrence is usually the result of inappropriate technique, early skin apposition, and
reformation of the abscess.
• Insufcient drainage leads to continued
inammation, prolonged healing, and stula
formation.
• Reasons for semi-acute recurrence include
missed loculations, prior intervention with
associated scarring, and destruction of natural
barriers to infection.
• Horseshoe abscesses recur more frequently
with a reported incidence between 18% and
50%, usually requiring multiple operations
before healing occurs.
Misdiagnosis
• Pilonidal disease, hidradenitis suppurativa,
tuberculosis, herpes simplex virus, HIV, and
inammatory bowel disease (specically,
Crohn’s disease) must be part of the differential diagnosis.
Special Considerations
Necrotizing Anorectal Infection (Fournier’s Gangrene)
• Necrotizing anorectal infections are rare.
• Medical risk factors commonly associated
with necrotizing soft tissue infections include
diabetes, hypertension, elderly age, obesity,
immunosuppression (especially when due to
malnutrition, liver disease, malignancies),
drug use, and recent surgery.
• Long-standing or inappropriately managed
perianal disease predates an episode of
necrotizing fasciitis, and 50–60% had underlying anorectal abscess as their inciting source.
Diagnosis
• Presenting symptoms include severe pain out
of proportion to exam, fever, chills, erythema,
and induration at the site (Fig.14.9).
• In polymicrobial and clostridial infections,
crepitance is often noted.
• As necrotizing soft tissue infections progress
along fascial planes, the extent of disease is
easily underestimated.
• White blood cell count, creatinine kinase, and
lactate are most helpful in estimating severity
of infection and conrming the diagnosis.
• When the diagnosis is unclear, imaging is recommended using CT abdomen/pelvis to identify the source and extent of infection.
188
B. R. Davis and K. R. Kasten
Fig. 14.10 Extensive soft tissue debridement of necrotizing soft tissue infection starting as an anorectal abscess
• Some advocate creation of a colostomy to help
with wound care after extensive dissection.
Fig. 14.9 Necrotizing soft tissue infection in a patient
with a supralevator stula and abscess inadequately
drained
Treatment
• Prompt diagnosis and treatment is necessary
to maximize survival.
• Treatment involves aggressive uid resuscitation and initiation of broad-spectrum antibiotics (penicillin g, metronidazole, third-generation
cephalosporin, gentamicin).
• Next, the patient undergoes surgical intervention with wide local excision of affected tissue
(Fig.14.10).
• Due to rapid spread, surgical excision should
extend beyond visibly infected tissues.
• It is common to return to the operating room
within 24–48 h to re-excise margins and to
ensure appropriate source control. A useful
adjunct when anorectal abscess incites necrotizing fasciitis involves the loose-seton technique, where multiple radial incisions are
made in the external sphincter at its outer
margins.
Outcomes
• Necrotizing fasciitis remains a lethal disease,
despite signicant advances in diagnosis, surgical care, and supportive management.
• Mortality rates in the literature span 4–80%;
however, most large studies demonstrate a
consistent range of 7–10%.
• Death is usually the result of sepsis and
sequelae of multi-organ system failure.
• The Fournier’s gangrene severity index (FGSI)
predicts mortality.
Anorectal Infections
inImmunosuppressed Patients
Hematologic Abnormalities
inImmunosuppression
• In patients with hematologic malignancies, or
those treated with myelosuppressive regimens, immunosuppression and low neutrophil
count produce an incidence of anorectal sepsis
approaching 10%.
• Diagnosis is often difcult and delayed due to
low neutrophil counts, whereby non-uctuant
14 Anorectal Abscess andFistula
189
induration with minimal erythema evades
untrained eyes.
• However, systemic complications of sepsis
are more likely in this patient population,
including death, with mortality approaches
60% when untreated.
• Antibiotics are standard of care, aimed at coverage of standard gastrointestinal ora using a
local antibiogram.
• For patients with absolute neutrophil count
(ANC) < 1000/mm3, antibiotics are rst-line
therapy with rates of resolution between 30%
and 90%.
• Patients with higher neutrophil counts will
demonstrate an abscess, which requires incision and drainage.
• Physical exam is limited in these patients, so
imaging studies are indicated for delineation
of size, extent, and involved structures.
– CT scans are rapid, easily obtained, and
demonstrate supralevator components with
high degree of accuracy.
– MRI with T1- and T2-weighted images
provides superior imaging for diagnosis,
particularly for possible necrotizing
infection.
• The decision on timing of surgical intervention is not always clear-cut.
• Patients with neutropenia suffer higher
rates of morbidity following surgery, and
mortality was upwards of 45% in one study
versus 9% in those treated only with
antibiotics.
• Rates of antibiotic failure in neutropenic
patients range between 30% and 37%.
• Surgical debridement is indicated for abscess
formation, lack of improvement, or development of necrotizing infection.
Human Immunodeciency Virus (HIV)
• There is little distinction between the management of HIV patients and otherwise healthy
individuals with anorectal abscess.
• In this patient population, alternative diagnoses including sexually transmitted infections
and CMV are also common.
Anal Fistula
Etiology
• A stula is dened as an abnormal connection between two epithelial-lined surfaces
such as a set of organs or vessels, which do
not normally connect, e.g., the connection
between the distal alimentary tract and the
integument.
• The incidence is believed to be 2 per 10,000/
year, while the prevalence is not truly
known.
• The etiology of anal stula is cryptoglandular
in 90% of cases, postoperative or traumatic in
3%, inammatory bowel disease 3%, as a
result of anal ssure 3%, and tuberculosis
related in less than 1% of cases.
• Cryptoglandular origin.
– 100 anatomical specimens, anal glands in
55% of specimens; in 33% the ducts penetrated the internal sphincter.
– 6–10 mucous-producing glands originating
from the anal crypts.
– Glands terminate variably into the submu-
cosa, internal sphincter, or intersphincteric
groove.
– Free channel for infection to pass from the
anal lumen deep into the sphincter
muscles.
– Anal crypts become blocked by inspissated
debris or stool.
– Infection develops at the anal glands, which
extends in a path of least resistance, forming an abscess in the intersphincteric space
leading to the development of a stula (36–
66% risk).
◦ Age less than 40, BMI exceeding
25 kg/m
emia, dermatosis, sedentary lifestyle,
regular alcohol intake, smoking, nonstula anorectal surgery, prolonged sitting on the toilet for defecation, and a
previous history of enteritis were independently correlated with a risk of anal
stula.
2
, prior diabetes, hyperlipid-
190
B. R. Davis and K. R. Kasten
Classication
• Anal stula can be characterized as simple or
complex (50%).
• The denition of a “complex” stula is not
standardized.
– Any stula that is high transsphincteric or
when a stulotomy would result in incontinence should be considered complex.
– Includes suprasphincteric, extrasphinc-
teric, all anterior transsphincteric stulas in
women.
– Fistulas caused by Crohn’s disease, malig-
nancy, surgery, and trauma.
• Anal stulas are also classied based on their
relationship to the anal sphincter complex.
Parks etal. (Table14.2) based on his analysis
of 400 cases of treated anal stula over a
15-year period.
• He anchored his classication system on the
external sphincter due to the importance it played
in the surgical management (Fig.14.11 a–d).
1. An intersphincteric stula (Fig.14.11a):
• 20–45% of cases
• Does not penetrate the external sphincter
• High blind track subtype, which has an
extension in the intersphincteric groove
cephalad toward the rectum
Table 14.2 Classication of stula-in-ano
Intersphincteric
Simple low intersphincteric
High blind tract
High tract with an opening in the rectum
High tract with rectal opening, no perineal opening
Extra-rectal extension
Secondary to pelvic disease
Transsphincteric
Uncomplicated
High blind tract
Suprasphincteric
Uncomplicated
Horseshoe extension
Extrasphincteric
Secondary to anal stula
Trauma related
Pelvic inammation
Inammatory bowel disease or other anal disease
2. A transsphincteric stula (Fig.14.11b):
• 30–60% of cases
• Penetrates the external sphincter below the
level of the puborectalis muscle exiting
into varying levels within the ischiorectal
fossa.
• A high blind track can end at the apex of
the ischiorectal fossa or alternatively pass
through the levator plate into the true pelvic cavity.
• Care should be taken not to iatrogenically
perforate the rectum, or an extrasphincteric
stula will be the result (Fig.14.12).
3. A suprasphincteric stula (Fig.14.11c):
• 20% of cases in the series by Parks etal.
has been reported at a much lower frequency by other authors (<2%).
• Track is over the top of the puborectalis
and then downward again through the levator plate to the ischiorectal fossa and nally
the skin.
• Abscess formation in this space can result
in a horseshoe extension around the
rectum.
4. Extrasphincteric stula (Fig.14.11d):
• 2–5% of cases
• Passes from the perineal skin through the
ischiorectal fat and levator muscles into the
rectum.
• It is outside the external sphincter complex
altogether.
• May result from a transsphincteric stula
with a high blind tract that penetrates
through the levator plate.
• May be due to trauma, inammatory bowel
disease, malignancy, or pelvic inammation that necessitates through the levators
to the perineal skin (ruptured appendicitis,
terminal ileal Crohn’s disease, or diverticulitis are the most common causes).
Diagnosis
• Fistula that results from cryptoglandular disease will usually be preceded by a history of
an anorectal abscess that was drained (either
purposefully or spontaneously).
ab
cd
14 Anorectal Abscess andFistula
191
Fig. 14.11 Classication of anal stula. (a) intersphincteric, (b) transsphincteric, (c) suprasphincteric, (d)
extrasphincteric
• Irritation of the anal margin skin ensues from
chronic moisture or from fecal contact.
• Pain may be a feature for patients with chronic
infection or ongoing inammation and is often
cyclical as a result of spontaneous abscess
formation and drainage.
• Physical exam ndings are usually pathognomonic for an anal stula with an opening on the
anal margin skin with heaped-up granulation tissue that is tender and often draining (Fig.14.13).
• The nature of the drainage can vary and may
be serous, purulent, or feculent depending on
the stula.
• Low transsphincteric stulas have been shown
Fig. 14.12 Flexible glide wire to delineate a transsphincteric stula with a high blind extension
to occur more often in the anterior location and
are less likely to be preceded by an abscess.
• External openings in the ischiorectal fossa are
• Bleeding is common due to the hypergranulation tissue that forms on the external opening.
usually the result of transsphincteric or suprasphincteric stula, and the examiner should